The Goose Bay high-frequency radar can be operated in a mode that allows the study of the temporal and spatial behavior of pulsating phenomena with a time scale of minutes. On November 28, 1983, an event occurred during which long-period pulsations were observed in the radar data. At this time, the field of view of the radar included a region of the cleft immediately to the east of the cusp. Combination of the radar data with HILAT magnetometer data had allowed the identification of the regions of the magnetosphere that mapped to the radar field of view. Pulsations with 10-min and 15-min periods were seen in a region mapping to the interior of the magnetosphere. They had high azimuthal wave number (17--25) and propagated eastward with a speed greater than 1 km/s. At the same time, eastward drifting patches of backscatter with a similar speed were seen in the region of antisunward convection that mapped either to the solar wind or the low-latitude boundary layer. A possible interpretation is that antisunward disturbances propagating along the magnetospheric boundary were driving surface waves within the magnetosphere. Possible types of disturbance that could cause such surface waves are flux-transfer events or Kelvin-Helmholtz waves.